/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.servlet.tags.form;

import javax.servlet.jsp.JspException;

/**
 * Abstract base class to provide common methods for implementing
 * databinding-aware JSP tags for rendering a <i>single</i>
 * HTML '{@code input}' element with a '{@code type}'
 * of '{@code checkbox}' or '{@code radio}'.
 *
 * @author Juergen Hoeller
 * @since 2.5.2
 */
@SuppressWarnings("serial")
public abstract class AbstractSingleCheckedElementTag extends AbstractCheckedElementTag {

    /**
     * The value of the '{@code value}' attribute.
     */
    private Object value;

    /**
     * The value of the '{@code label}' attribute.
     */
    private Object label;

    /**
     * Get the value of the '{@code value}' attribute.
     */
    protected Object getValue() {
        return this.value;
    }

    /**
     * Set the value of the '{@code value}' attribute.
     * May be a runtime expression.
     */
    public void setValue(Object value) {
        this.value = value;
    }

    /**
     * Get the value of the '{@code label}' attribute.
     */
    protected Object getLabel() {
        return this.label;
    }

    /**
     * Set the value of the '{@code label}' attribute.
     * May be a runtime expression.
     */
    public void setLabel(Object label) {
        this.label = label;
    }

    /**
     * Renders the '{@code input(radio)}' element with the configured
     * {@link #setValue(Object) value}. Marks the element as checked if the
     * value matches the {@link #getValue bound value}.
     */
    @Override
    protected int writeTagContent(TagWriter tagWriter) throws JspException {
        tagWriter.startTag("input");
        String id = resolveId();
        writeOptionalAttribute(tagWriter, "id", id);
        writeOptionalAttribute(tagWriter, "name", getName());
        writeOptionalAttributes(tagWriter);
        writeTagDetails(tagWriter);
        tagWriter.endTag();

        Object resolvedLabel = evaluate("label", getLabel());
        if (resolvedLabel != null) {
            tagWriter.startTag("label");
            tagWriter.writeAttribute("for", id);
            tagWriter.appendValue(convertToDisplayString(resolvedLabel));
            tagWriter.endTag();
        }

        return SKIP_BODY;
    }

    /**
     * Write the details for the given primary tag:
     * i.e. special attributes and the tag's value.
     */
    protected abstract void writeTagDetails(TagWriter tagWriter) throws JspException;

}
